System for a surveillance marker in robotic-assisted surgery

ABSTRACT

Devices, systems, and methods for providing a surveillance marker configured to detecting movement of a dynamic reference base attached to a patient a robot-assisted surgical procedure are provided. The surveillance marker and the dynamic reference base are connected to a bony structure independent of each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/448,670 filed on Mar. 3, 2017 which is acontinuation-in-part of U.S. patent application Ser. No. 15/157,444filed May 18, 2016, which is a continuation-in-part application of U.S.patent application Ser. No. 15/095,883 filed on Apr. 11, 2016 (publishedas U.S. Patent Publication No. 2016/0220320 A1), which is acontinuation-in-part application of U.S. patent application Ser. No.14/062,707 filed on Oct. 24, 2013 (published as U.S. Patent PublicationNo. 2014/0275955 A1), which is a continuation-in-part application ofU.S. patent application Ser. No. 13/924,505 filed on Jun. 21, 2013(published as U.S. Patent Publication No. 2013/0345718 A1, withcorrected publication as U.S. Patent Publication No. 2016/0242849 A9),which is a nonprovisional patent application that claims priority toU.S. provisional patent application No. 61/662,702 filed on Jun. 21,2012, and claims priority to U.S. provisional patent application No.61/800,527 filed on Mar. 15, 2013, the entire contents of all of whichare incorporated herein by reference. This application also claimspriority to Provisional Patent Application Ser. No. 62/608,188 filed onDec. 20, 2017, which is incorporated in entirety herein.

FIELD OF THE INVENTION

The present disclosure relates to surveillance marker implementation forrobot-assisted surgical techniques.

BACKGROUND OF THE INVENTION

Various medical procedures require the accurate localization of athree-dimensional position of a surgical instrument within the body inorder to effect optimized treatment. For example, some surgicalprocedures to fuse vertebrae require that a surgeon drill multiple holesinto the bone structure at specific locations. To achieve high levels ofmechanical integrity in the fusing system, and to balance the forcescreated in the bone structure, it is necessary that the holes aredrilled at the correct location. Vertebrae, like most bone structures,have complex shapes including non-planar curved surfaces making accurateand perpendicular drilling difficult.

Conventionally, using currently-available systems and methods, a surgeonmanually holds and positions a drill guide tube by using a guidancesystem to overlay the drill tube's position onto a three dimensionalimage of the anatomical structures of a patient, for example, bonestructures of the patient. This manual process is both tedious, timeconsuming, and error-prone. Further, whether the surgery can beconsidered successful largely depends upon the dexterity of the surgeonwho performs it. Thus, there is a need for the use of robot assistedsurgery to more accurately position surgical instruments and moreaccurately depict the position of those instruments in relation to theanatomical structures of the patient.

Currently, limited robotic assistance for surgical procedures isavailable. For example, certain systems allow a user to control arobotic actuator. These systems convert a surgeon's gross movements intomicro-movements of the robotic actuator to more accurately position andsteady the surgical instruments when undergoing surgery. Although thesesystems may aid in eliminating hand tremor and provide the surgeon withimproved ability to work through a small opening, like many of therobots commercially available today, these systems are expensive,obtrusive, and require a cumbersome setup for the robot in relation tothe patient and the user (e.g., a surgeon).

In some robotic-assisted systems, registration techniques may be used inorder to properly track surgical instruments in relation to 2D and/or 3Dimages of the patient's target anatomy. As previously discussed inparent applications to the present disclosure (listed above), a dynamicreference base (DRB) may be physically attached to bony structures of apatient. After registration of the markers to images of the patient'sanatomy, the DRB may be used as a reference point in order to properlydisplay the position of navigated surgical instruments in relation toimages of the patient's anatomy. In the event the DRB is shifted ordislodged, the registration process may need to be reinitiated so ensureproper registration and that the visual display of the navigatedinstruments relative to images of the patient's anatomy are accurate toreal-life movements of the instruments.

One way to determine if the DRB has been dislodged or move is throughthe use of a surveillance maker. The use of surveillance makers has beenpreviously described in U.S. patent application Ser. No. 13/294,505 thecontents of which are incorporated herein by reference. The surveillancemarker is a single tracked marker attached to the patient in a locationother than the location of the DRB that tracks patient position. If thepatient is moved relative to the tracking cameras, the surveillancemarker and DRB would be expected to move together by the same amount,with no relative movement between DRB and surveillance marker. However,movement of the surveillance marker relative to tracking markers on theDRB is an indicator that the DRB may have been accidentally dislodged.

The surveillance marker may require additional preparation and surgicalincision of the patient at the location where the surveillance marker isto be applied. Thus, there is a need to allow a surgeon to attach thesurveillance marker to the patient using the same incision as was usedfor DRB placement. To improve functionality, the surveillance marker maynot rigidly interface with the DRB.

Accordingly, there exists a need for a surveillance marker that does notrigidly interface with the DRB while still effectively detecting DRBdislodgment. This may be accomplished by the present disclosure byattaching the surveillance marker to bone near the DRB. For example,having the surveillance marker on a post that does not touch the DRB.

SUMMARY OF THE INVENTION

To meet this and other needs, devices, systems, and methods fordetecting the presence of unintended movement of a surgical instrumentduring a surgical procedure are provided.

According to one exemplary embodiment, the present disclosure provides asystem for checking accuracy of registration of a patient to a surgicalrobot. The system includes a dynamic reference base including at leastone array marker, a dynamic reference base post connected to the dynamicreference base, a surveillance marker disposed at a predetermineddistance from the dynamic reference base; and a surveillance marker postconnected to the surveillance marker and disposed independent of thedynamic reference base post. The surveillance marker post and thedynamic reference base are attached to different portions of a bonystructure.

According to another exemplary embodiment, the present disclosureprovides a system for accuracy of registration of a patient to asurgical robot. The system comprising a dynamic reference base includingat least one array marker, a dynamic reference base post associated withthe dynamic reference base, a surveillance marker disposed at apredetermined distance from the dynamic reference base, a surveillancemarker post associated with the surveillance marker; and a temporarygrouping element configured to receive the surveillance marker post andthe dynamic reference base post. The surveillance marker post and thedynamic reference base are attached to different portions of a bonystructure while received in the temporary grouping element. Thetemporary grouping member may be configured to be removed from thesurveillance marker post and dynamic reference base post afterattachment to the bony structure.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and the following detailed description of certainembodiments thereof may be understood by reference to the followingfigures:

FIG. 1 is an overhead view of a potential arrangement for locations ofthe robotic system, patient, surgeon, and other medical personnel duringa surgical procedure;

FIG. 2 illustrates the robotic system including positioning of thesurgical robot and the camera relative to the patient according to oneembodiment;

FIG. 3 illustrates a surgical robotic system in accordance with anexemplary embodiment;

FIG. 4 illustrates a portion of a surgical robot in accordance with anexemplary embodiment;

FIG. 5 illustrates a block diagram of a surgical robot in accordancewith an exemplary embodiment;

FIG. 6 illustrates a surgical robot in accordance with an exemplaryembodiment;

FIGS. 7A-7C illustrate an end effector in accordance with an exemplaryembodiment;

FIG. 8 illustrates a surgical instrument and the end effector, beforeand after, inserting the surgical instrument into the guide tube of theend effector according to one embodiment;

FIGS. 9A-9C illustrate portions of an end effector and robot arm inaccordance with an exemplary embodiment;

FIG. 10 illustrates a dynamic reference array, an imaging array, andother components in accordance with an exemplary embodiment;

FIG. 11 illustrates a method of registration in accordance with anexemplary embodiment;

FIG. 12A-12B illustrate embodiments of imaging devices according toexemplary embodiments;

FIGS. 13A-13B illustrate a surveillance marker in accordance withexemplary embodiments of the present disclosure;

FIGS. 14A-14B illustrate a surveillance marker in accordance withexemplary embodiments of the present disclosure; and

FIG. 15 illustrates a surveillance marker in accordance with anexemplary embodiment of the present disclosure.

FIGS. 16A and 16B illustrates a surveillance marker in accordance in oneembodiment of the present disclosure.

FIGS. 17A and 17B illustrates a surveillance marker in accordance withan exemplary embodiment of the present disclosure.

FIG. 18 illustrates yet another embodiment of a multiple surveillancemarkers in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the present disclosure is not limited in itsapplication to the details of construction and the arrangement ofcomponents set forth in the description herein or illustrated in thedrawings. The teachings of the present disclosure may be used andpracticed in other embodiments and practiced or carried out in variousways. Also, it is to be understood that the phraseology and terminologyused herein is for the purpose of description and should not be regardedas limiting. The use of “including,” “comprising,” or “having” andvariations thereof herein is meant to encompass the items listedthereafter and equivalents thereof as well as additional items. Unlessspecified or limited otherwise, the terms “mounted,” “connected,”“supported,” and “coupled” and variations thereof are used broadly andencompass both direct and indirect mountings, connections, supports, andcouplings. Further, “connected” and “coupled” are not restricted tophysical or mechanical connections or couplings.

The following discussion is presented to enable a person skilled in theart to make and use embodiments of the present disclosure. Variousmodifications to the illustrated embodiments will be readily apparent tothose skilled in the art, and the principles herein can be applied toother embodiments and applications without departing from embodiments ofthe present disclosure. Thus, the embodiments are not intended to belimited to embodiments shown, but are to be accorded the widest scopeconsistent with the principles and features disclosed herein. Thefollowing detailed description is to be read with reference to thefigures, in which like elements in different figures have like referencenumerals. The figures, which are not necessarily to scale, depictselected embodiments and are not intended to limit the scope of theembodiments. Skilled artisans will recognize the examples providedherein have many useful alternatives and fall within the scope of theembodiments.

Turning now to the drawing, FIGS. 1 and 2 illustrate a surgical robotsystem 100 in accordance with an exemplary embodiment. Surgical robotsystem 100 may include, for example, a surgical robot 102, one or morerobot arms 104, a base 106, a display 110, an end effector 112, forexample, including a guide tube 114, and one or more tracking markers118. The surgical robot system 100 may include a patient tracking device116 also including one or more tracking markers 118, which is adapted tobe secured directly to the patient 210 (e.g., to the bone of the patient210). The surgical robot system 100 may also utilize a camera 200, forexample, positioned on a camera stand 202. The camera stand 202 can haveany suitable configuration to move, orient, and support the camera 200in a desired position. The camera 200 may include any suitable camera orcameras, such as one or more infrared cameras (e.g., bifocal orstereophotogrammetric cameras), able to identify, for example, activeand passive tracking markers 118 in a given measurement volume viewablefrom the perspective of the camera 200. The camera 200 may scan thegiven measurement volume and detect the light that comes from themarkers 118 in order to identify and determine the position of themarkers 118 in three dimensions. For example, active markers 118 mayinclude infrared-emitting markers that are activated by an electricalsignal (e.g., infrared light emitting diodes (LEDs)), and passivemarkers 118 may include retro-reflective markers that reflect infraredlight (e.g., they reflect incoming IR radiation into the direction ofthe incoming light), for example, emitted by illuminators on the camera200 or other suitable device.

FIGS. 1 and 2 illustrate a potential configuration for the placement ofthe surgical robot system 100 in an operating room environment. Forexample, the robot 102 may be positioned near or next to patient 210.Although depicted near the head of the patient 210, it will beappreciated that the robot 102 can be positioned at any suitablelocation near the patient 210 depending on the area of the patient 210undergoing the operation. The camera 200 may be separated from the robotsystem 100 and positioned at the foot of patient 210. This locationallows the camera 200 to have a direct visual line of sight to thesurgical field 208. Again, it is contemplated that the camera 200 may belocated at any suitable position having line of sight to the surgicalfield 208. In the configuration shown, the surgeon 120 may be positionedacross from the robot 102, but is still able to manipulate the endeffector 112 and the display 110. A surgical assistant 126 may bepositioned across from the surgeon 120 again with access to both the endeffector 112 and the display 110. If desired, the locations of thesurgeon 120 and the assistant 126 may be reversed. The traditional areasfor the anesthesiologist 122 and the nurse or scrub tech 124 remainunimpeded by the locations of the robot 102 and camera 200.

With respect to the other components of the robot 102, the display 110can be attached to the surgical robot 102 and in other exemplaryembodiments, display 110 can be detached from surgical robot 102, eitherwithin a surgical room with the surgical robot 102, or in a remotelocation. End effector 112 may be coupled to the robot arm 104 andcontrolled by at least one motor. In exemplary embodiments, end effector112 can comprise a guide tube 114, which is able to receive and orient asurgical instrument 608 (described further herein) used to performsurgery on the patient 210. As used herein, the term “end effector” isused interchangeably with the terms “end-effectuator” and “effectuatorelement.” Although generally shown with a guide tube 114, it will beappreciated that the end effector 112 may be replaced with any suitableinstrumentation suitable for use in surgery. In some embodiments, endeffector 112 can comprise any known structure for effecting the movementof the surgical instrument 608 in a desired manner.

The surgical robot 102 is able to control the translation andorientation of the end effector 112. The robot 102 is able to move endeffector 112 along x-, y-, and z-axes, for example. The end effector 112can be configured for selective rotation about one or more of the x-,y-, and z-axis, and a Z Frame axis (such that one or more of the EulerAngles (e.g., roll, pitch, and/or yaw) associated with end effector 112can be selectively controlled). In some exemplary embodiments, selectivecontrol of the translation and orientation of end effector 112 canpermit performance of medical procedures with significantly improvedaccuracy compared to conventional robots that utilize, for example, asix degree of freedom robot arm comprising only rotational axes. Forexample, the surgical robot system 100 may be used to operate on patient210, and robot arm 104 can be positioned above the body of patient 210,with end effector 112 selectively angled relative to the z-axis towardthe body of patient 210.

In some exemplary embodiments, the position of the surgical instrument608 can be dynamically updated so that surgical robot 102 can be awareof the location of the surgical instrument 608 at all times during theprocedure. Consequently, in some exemplary embodiments, surgical robot102 can move the surgical instrument 608 to the desired position quicklywithout any further assistance from a physician (unless the physician sodesires). In some further embodiments, surgical robot 102 can beconfigured to correct the path of the surgical instrument 608 if thesurgical instrument 608 strays from the selected, preplanned trajectory.In some exemplary embodiments, surgical robot 102 can be configured topermit stoppage, modification, and/or manual control of the movement ofend effector 112 and/or the surgical instrument 608. Thus, in use, inexemplary embodiments, a physician or other user can operate the system100, and has the option to stop, modify, or manually control theautonomous movement of end effector 112 and/or the surgical instrument608. Further details of surgical robot system 100 including the controland movement of a surgical instrument 608 by surgical robot 102 can befound in co-pending U.S. patent application Ser. No. 13/924,505, whichis incorporated herein by reference in its entirety.

The robotic surgical system 100 can comprise one or more trackingmarkers 118 configured to track the movement of robot arm 104, endeffector 112, patient 210, and/or the surgical instrument 608 in threedimensions. In exemplary embodiments, a plurality of tracking markers118 can be mounted (or otherwise secured) thereon to an outer surface ofthe robot 102, such as, for example and without limitation, on base 106of robot 102, on robot arm 104, or on the end effector 112. In exemplaryembodiments, at least one tracking marker 118 of the plurality oftracking markers 118 can be mounted or otherwise secured to the endeffector 112. One or more tracking markers 118 can further be mounted(or otherwise secured) to the patient 210. In exemplary embodiments, theplurality of tracking markers 118 can be positioned on the patient 210spaced apart from the surgical field 208 to reduce the likelihood ofbeing obscured by the surgeon, surgical tools, or other parts of therobot 102. Further, one or more tracking markers 118 can be furthermounted (or otherwise secured) to the surgical tools 608 (e.g., a screwdriver, dilator, implant inserter, or the like). Thus, the trackingmarkers 118 enable each of the marked objects (e.g., the end effector112, the patient 210, and the surgical tools 608) to be tracked by therobot 102. In exemplary embodiments, system 100 can use trackinginformation collected from each of the marked objects to calculate theorientation and location, for example, of the end effector 112, thesurgical instrument 608 (e.g., positioned in the tube 114 of the endeffector 112), and the relative position of the patient 210.

In exemplary embodiments, one or more of markers 118 may be opticalmarkers. In some embodiments, the positioning of one or more trackingmarkers 118 on end effector 112 can maximize the accuracy of thepositional measurements by serving to check or verify the position ofend effector 112. Further details of surgical robot system 100 includingthe control, movement and tracking of surgical robot 102 and of asurgical instrument 608 can be found in co-pending U.S. patentapplication Ser. No. 13/924,505, which is incorporated herein byreference in its entirety.

Exemplary embodiments include one or more markers 118 coupled to thesurgical instrument 608. In exemplary embodiments, these markers 118,for example, coupled to the patient 210 and surgical instruments 608, aswell as markers 118 coupled to the end effector 112 of the robot 102 cancomprise conventional infrared light-emitting diodes (LEDs) or anOptotrak® diode capable of being tracked using a commercially availableinfrared optical tracking system such as Optotrak®. Optotrak® is aregistered trademark of Northern Digital Inc., Waterloo, Ontario,Canada. In other embodiments, markers 118 can comprise conventionalreflective spheres capable of being tracked using a commerciallyavailable optical tracking system such as Polaris Spectra. PolarisSpectra is also a registered trademark of Northern Digital, Inc. In anexemplary embodiment, the markers 118 coupled to the end effector 112are active markers which comprise infrared light-emitting diodes whichmay be turned on and off, and the markers 118 coupled to the patient 210and the surgical instruments 608 comprise passive reflective spheres.

In exemplary embodiments, light emitted from and/or reflected by markers118 can be detected by camera 200 and can be used to monitor thelocation and movement of the marked objects. In alternative embodiments,markers 118 can comprise a radio-frequency and/or electromagneticreflector or transceiver and the camera 200 can include or be replacedby a radio-frequency and/or electromagnetic transceiver.

Similar to surgical robot system 100, FIG. 3 illustrates a surgicalrobot system 300 and camera stand 302, in a docked configuration,consistent with an exemplary embodiment of the present disclosure.Surgical robot system 300 may comprise a robot 301 including a display304, upper arm 306, lower arm 308, end effector 310, vertical column312, casters 314, cabinet 316, tablet drawer 318, connector panel 320,control panel 322, and ring of information 324. Camera stand 302 maycomprise camera 326. These components are described in greater withrespect to FIG. 5 . FIG. 3 illustrates the surgical robot system 300 ina docked configuration where the camera stand 302 is nested with therobot 301, for example, when not in use. It will be appreciated by thoseskilled in the art that the camera 326 and robot 301 may be separatedfrom one another and positioned at any appropriate location during thesurgical procedure, for example, as shown in FIGS. 1 and 2 . FIG. 4illustrates a base 400 consistent with an exemplary embodiment of thepresent disclosure. Base 400 may be a portion of surgical robot system300 and comprise cabinet 316. Cabinet 316 may house certain componentsof surgical robot system 300 including but not limited to a battery 402,a power distribution module 404, a platform interface board module 406,a computer 408, a handle 412, and a tablet drawer 414. The connectionsand relationship between these components is described in greater detailwith respect to FIG. 5 .

FIG. 5 illustrates a block diagram of certain components of an exemplaryembodiment of surgical robot system 300. Surgical robot system 300 maycomprise platform subsystem 502, computer subsystem 504, motion controlsubsystem 506, and tracking subsystem 532. Platform subsystem 502 mayfurther comprise battery 402, power distribution module 404, platforminterface board module 406, and tablet charging station 534. Computersubsystem 504 may further comprise computer 408, display 304, andspeaker 536. Motion control subsystem 506 may further comprise drivercircuit 508, motors 510, 512, 514, 516, 518, stabilizers 520, 522, 524,526, end effector 310, and controller 538. Tracking subsystem 532 mayfurther comprise position sensor 540 and camera converter 542. System300 may also comprise a foot pedal 544 and tablet 546.

Input power is supplied to system 300 via a power source 548 which maybe provided to power distribution module 404. Power distribution module404 receives input power and is configured to generate different powersupply voltages that are provided to other modules, components, andsubsystems of system 300. Power distribution module 404 may beconfigured to provide different voltage supplies to platform interfacemodule 406, which may be provided to other components such as computer408, display 304, speaker 536, driver 508 to, for example, power motors512, 514, 516, 518 and end effector 310, motor 510, ring 324, cameraconverter 542, and other components for system 300 for example, fans forcooling the electrical components within cabinet 316.

Power distribution module 404 may also provide power to other componentssuch as tablet charging station 534 that may be located within tabletdrawer 318. Tablet charging station 534 may be in wireless or wiredcommunication with tablet 546 for charging table 546. Tablet 546 may beused by a surgeon consistent with the present disclosure and describedherein. Power distribution module 404 may also be connected to battery402, which serves as temporary power source in the event that powerdistribution module 404 does not receive power from input power 548. Atother times, power distribution module 404 may serve to charge battery402 if necessary.

Other components of platform subsystem 502 may also include connectorpanel 320, control panel 322, and ring 324. Connector panel 320 mayserve to connect different devices and components to system 300 and/orassociated components and modules. Connector panel 320 may contain oneor more ports that receive lines or connections from differentcomponents. For example, connector panel 320 may have a ground terminalport that may ground system 300 to other equipment, a port to connectfoot pedal 544 to system 300, a port to connect to tracking subsystem532, which may comprise position sensor 540, camera converter 542, andcameras 326 associated with camera stand 302. Connector panel 320 mayalso include other ports to allow USB, Ethernet, HDMI communications toother components, such as computer 408.

Control panel 322 may provide various buttons or indicators that controloperation of system 300 and/or provide information regarding system 300.For example, control panel 322 may include buttons to power on or offsystem 300, lift or lower vertical column 312, and lift or lowerstabilizers 520-526 that may be designed to engage casters 314 to locksystem 300 from physically moving. Other buttons may stop system 300 inthe event of an emergency, which may remove all motor power and applymechanical brakes to stop all motion from occurring. Control panel 322may also have indicators notifying the user of certain system conditionssuch as a line power indicator or status of charge for battery 402.

Ring 324 may be a visual indicator to notify the user of system 300 ofdifferent modes that system 300 is operating under and certain warningsto the user.

Computer subsystem 504 includes computer 408, display 304, and speaker536. Computer 504 includes an operating system and software to operatesystem 300. Computer 504 may receive and process information from othercomponents (for example, tracking subsystem 532, platform subsystem 502,and/or motion control subsystem 506) in order to display information tothe user. Further, computer subsystem 504 may also include speaker 536to provide audio to the user.

Tracking subsystem 532 may include position sensor 504 and converter542. Tracking subsystem 532 may correspond to camera stand 302 includingcamera 326 as described with respect to FIG. 3 . Position sensor 504 maybe camera 326. Tracking subsystem may track the location of certainmarkers that are located on the different components of system 300and/or instruments used by a user during a surgical procedure. Thistracking may be conducted in a manner consistent with the presentdisclosure including the use of infrared technology that tracks thelocation of active or passive elements, such as LEDs or reflectivemarkers, respectively. The location, orientation, and position ofstructures having these types of markers may be provided to computer 408which may be shown to a user on display 304. For example, a surgicalinstrument 608 having these types of markers and tracked in this manner(which may be referred to as a navigational space) may be shown to auser in relation to a three dimensional image of a patient's anatomicalstructure. Motion control subsystem 506 may be configured to physicallymove vertical column 312, upper arm 306, lower arm 308, or rotate endeffector 310. The physical movement may be conducted through the use ofone or more motors 510-518. For example, motor 510 may be configured tovertically lift or lower vertical column 312. Motor 512 may beconfigured to laterally move upper arm 308 around a point of engagementwith vertical column 312 as shown in FIG. 3 . Motor 514 may beconfigured to laterally move lower arm 308 around a point of engagementwith upper arm 308 as shown in FIG. 3 . Motors 516 and 518 may beconfigured to move end effector 310 in a manner such that one maycontrol the roll and one may control the tilt, thereby providingmultiple angles that end effector 310 may be moved. These movements maybe achieved by controller 538 which may control these movements throughload cells disposed on end effector 310 and activated by a user engagingthese load cells to move system 300 in a desired manner.

Moreover, system 300 may provide for automatic movement of verticalcolumn 312, upper arm 306, and lower arm 308 through a user indicatingon display 304 (which may be a touchscreen input device) the location ofa surgical instrument or component on three dimensional image of thepatient's anatomy on display 304. The user may initiate this automaticmovement by stepping on foot pedal 544 or some other input means.

FIG. 6 illustrates a surgical robot system 600 consistent with anexemplary embodiment. Surgical robot system 600 may comprise endeffector 602, robot arm 604, guide tube 606, instrument 608, and robotbase 610. Instrument tool 608 may be attached to a tracking array 612including one or more tracking markers (such as markers 118) and have anassociated trajectory 614. Trajectory 614 may represent a path ofmovement that instrument tool 608 is configured to travel once it ispositioned through or secured in guide tube 606, for example, a path ofinsertion of instrument tool 608 into a patient. In an exemplaryoperation, robot base 610 may be configured to be in electroniccommunication with robot arm 604 and end effector 602 so that surgicalrobot system 600 may assist a user (for example, a surgeon) in operatingon the patient 210. Surgical robot system 600 may be consistent withpreviously described surgical robot system 100 and 300.

A tracking array 612 may be mounted on instrument 608 to monitor thelocation and orientation of instrument tool 608. The tracking array 612may be attached to an instrument 608 and may comprise tracking markers804. As best seen in FIG. 8 , tracking markers 804 may be, for example,light emitting diodes and/or other types of reflective markers (e.g.,markers 118 as described elsewhere herein). The tracking devices may beone or more line of sight devices associated with the surgical robotsystem. As an example, the tracking devices may be one or more cameras200, 326 associated with the surgical robot system 100, 300 and may alsotrack tracking array 612 for a defined domain or relative orientationsof the instrument 608 in relation to the robot arm 604, the robot base610, end effector 602, and/or the patient 210. The tracking devices maybe consistent with those structures described in connection with camerastand 302 and tracking subsystem 532.

FIGS. 7A, 7B, and 7C illustrate a top view, front view, and side view,respectively, of end effector 602 consistent with an exemplaryembodiment. End effector 602 may comprise one or more tracking markers702. Tracking markers 702 may be light emitting diodes or other types ofactive and passive markers, such as tracking markers 118 that have beenpreviously described. In an exemplary embodiment, the tracking markers702 are active infrared-emitting markers that are activated by anelectrical signal (e.g., infrared light emitting diodes (LEDs)). Thus,tracking markers 702 may be activated such that the infrared markers 702are visible to the camera 200, 326 or may be deactivated such that theinfrared markers 702 are not visible to the camera 200, 326. Thus, whenthe markers 702 are active, the end effector 602 may be controlled bythe system 100, 300, 600, and when the markers 702 are deactivated, theend effector 602 may be locked in position and unable to be moved by thesystem 100, 300, 600.

Markers 702 may be disposed on or within end effector 602 in a mannersuch that the markers 702 are visible by one or more cameras 200, 326 orother tracking devices associated with the surgical robot system 100,300, 600. The camera 200, 326 or other tracking devices may track endeffector 602 as it moves to different positions and viewing angles byfollowing the movement of tracking markers 702. The location of markers702 and/or end effector 602 may be shown on a display 110, 304associated with the surgical robot system 100, 300, 600, for example,display 110 as shown in FIG. 2 and/or display 304 shown in FIG. 3 . Thisdisplay 110, 304 may allow a user to ensure that end effector 602 is ina desirable position in relation to robot arm 604, robot base 610, thepatient 210, and/or the user.

For example, as shown in FIG. 7A, markers 702 may be placed around thesurface of end effector 602 so that a tracking device placed away fromthe surgical field 208 and facing toward the robot 102, 301 and thecamera 200, 326 is able to view at least 3 of the markers 702 through arange of common orientations of the end effector 602 relative to thetracking device 100, 300, 600. For example, distribution of markers 702in this way allows end effector 602 to be monitored by the trackingdevices when end effector 602 is translated and rotated in the surgicalfield 208.

In addition, in exemplary embodiments, end effector 602 may be equippedwith infrared (IR) receivers that can detect when an external camera200, 326 is getting ready to read markers 702. Upon this detection, endeffector 602 may then illuminate markers 702. The detection by the IRreceivers that the external camera 200, 326 is ready to read markers 702may signal the need to synchronize a duty cycle of markers 702, whichmay be light emitting diodes, to an external camera 200, 326. This mayalso allow for lower power consumption by the robotic system as a whole,whereby markers 702 would only be illuminated at the appropriate timeinstead of being illuminated continuously. Further, in exemplaryembodiments, markers 702 may be powered off to prevent interference withother navigation tools, such as different types of surgical instruments608.

FIG. 8 depicts one type of surgical instrument 608 including a trackingarray 612 and tracking markers 804. Tracking markers 804 may be of anytype described herein including but not limited to light emitting diodesor reflective spheres. Markers 804 are monitored by tracking devicesassociated with the surgical robot system 100, 300, 600 and may be oneor more of the line of sight cameras 200, 326. The cameras 200, 326 maytrack the location of instrument 608 based on the position andorientation of tracking array 612 and markers 804. A user, such as asurgeon 120, may orient instrument 608 in a manner so that trackingarray 612 and markers 804 are sufficiently recognized by the trackingdevice or camera 200, 326 to display instrument 608 and markers 804 on,for example, display 110 of the exemplary surgical robot system.

The manner in which a surgeon 120 may place instrument 608 into guidetube 606 of the end effector 602 and adjust the instrument 608 isevident in FIG. 8 . The hollow tube or guide tube 114, 606 of the endeffector 112, 310, 602 is sized and configured to receive at least aportion of the surgical instrument 608. The guide tube 114, 606 isconfigured to be oriented by the robot arm 104 such that insertion andtrajectory for the surgical instrument 608 is able to reach a desiredanatomical target within or upon the body of the patient 210. Thesurgical instrument 608 may include at least a portion of a generallycylindrical instrument. Although a screw driver is exemplified as thesurgical tool 608, it will be appreciated that any suitable surgicaltool 608 may be positioned by the end effector 602. By way of example,the surgical instrument 608 may include one or more of a guide wire,cannula, a retractor, a drill, a reamer, a screw driver, an insertiontool, a removal tool, or the like. Although the hollow tube 114, 606 isgenerally shown as having a cylindrical configuration, it will beappreciated by those of skill in the art that the guide tube 114, 606may have any suitable shape, size and configuration desired toaccommodate the surgical instrument 608 and access the surgical site.

FIGS. 9A-9C illustrate end effector 602 and a portion of robot arm 604consistent with an exemplary embodiment. End effector 602 may furthercomprise body 1202 and clamp 1204. Clamp 1204 may comprise handle 1206,balls 1208, spring 1210, and lip 1212. Robot arm 604 may furthercomprise depressions 1214, mounting plate 1216, lip 1218, and magnets1220.

End effector 602 may mechanically interface and/or engage with thesurgical robot system and robot arm 604 through one or more couplings.For example, end effector 602 may engage with robot arm 604 through alocating coupling and/or a reinforcing coupling. Through thesecouplings, end effector 602 may fasten with robot arm 604 outside aflexible and sterile barrier. In an exemplary embodiment, the locatingcoupling may be a magnetically kinematic mount and the reinforcingcoupling may be a five bar over center clamping linkage.

With respect to the locating coupling, robot arm 604 may comprisemounting plate 1216, which may be non-magnetic material, one or moredepressions 1214, lip 1218, and magnets 1220. Magnet 1220 is mountedbelow each of depressions 1214. Portions of clamp 1204 may comprisemagnetic material and be attracted by one or more magnets 1220. Throughthe magnetic attraction of clamp 1204 and robot arm 604, balls 1208become seated into respective depressions 1214. For example, balls 1208as shown in FIG. 9B would be seated in depressions 1214 as shown in FIG.9A. This seating may be considered a magnetically-assisted kinematiccoupling. Magnets 1220 may be configured to be strong enough to supportthe entire weight of end effector 602 regardless of the orientation ofend effector 602. The locating coupling may be any style of kinematicmount that uniquely restrains six degrees of freedom.

With respect to the reinforcing coupling, portions of clamp 1204 may beconfigured to be a fixed ground link and as such clamp 1204 may serve asa five bar linkage. Closing clamp handle 1206 may fasten end effector602 to robot arm 604 as lip 1212 and lip 1218 engage clamp 1204 in amanner to secure end effector 602 and robot arm 604. When clamp handle1206 is closed, spring 1210 may be stretched or stressed while clamp1204 is in a locked position. The locked position may be a position thatprovides for linkage past center. Because of a closed position that ispast center, the linkage will not open absent a force applied to clamphandle 1206 to release clamp 1204. Thus, in a locked position endeffector 602 may be robustly secured to robot arm 604.

Spring 1210 may be a curved beam in tension. Spring 1210 may becomprised of a material that exhibits high stiffness and high yieldstrain such as virgin PEEK (poly-ether-ether-ketone). The linkagebetween end effector 602 and robot arm 604 may provide for a sterilebarrier between end effector 602 and robot arm 604 without impedingfastening of the two couplings.

The reinforcing coupling may be a linkage with multiple spring members.The reinforcing coupling may latch with a cam or friction basedmechanism. The reinforcing coupling may also be a sufficiently powerfulelectromagnet that will support fastening end-effector 102 to robot arm604. The reinforcing coupling may be a multi-piece collar completelyseparate from either end effector 602 and/or robot arm 604 that slipsover an interface between end effector 602 and robot arm 604 andtightens with a screw mechanism, an over center linkage, or a cammechanism.

Referring to FIGS. 10 and 11 , prior to or during a surgical procedure,certain registration procedures may be conducted in order to trackobjects and a target anatomical structure of the patient 210 both in anavigation space and an image space. In order to conduct suchregistration, a registration system 1400 may be used as illustrated inFIG. 10 .

In order to track the position of the patient 210, a patient trackingdevice 116 may include a patient fixation instrument 1402 to be securedto a rigid anatomical structure of the patient 210 and a dynamicreference base (DRB) 1404 may be securely attached to the patientfixation instrument 1402. For example, patient fixation instrument 1402may be inserted into opening 1406 of dynamic reference base 1404.Dynamic reference base 1404 may contain markers 1408 that are visible totracking devices, such as tracking subsystem 532. These markers 1408 maybe optical markers or reflective spheres, such as tracking markers 118,as previously discussed herein.

Patient fixation instrument 1402 is attached to a rigid anatomy of thepatient 210 and may remain attached throughout the surgical procedure.In an exemplary embodiment, patient fixation instrument 1402 is attachedto a rigid area of the patient 210, for example, a bone that is locatedaway from the targeted anatomical structure subject to the surgicalprocedure. In order to track the targeted anatomical structure, dynamicreference base 1404 is associated with the targeted anatomical structurethrough the use of a registration fixture that is temporarily placed onor near the targeted anatomical structure in order to register thedynamic reference base 1404 with the location of the targeted anatomicalstructure.

A registration fixture 1410 is attached to patient fixation instrument1402 through the use of a pivot arm 1412. Pivot arm 1412 is attached topatient fixation instrument 1402 by inserting patient fixationinstrument 1402 through an opening 1414 of registration fixture 1410.Pivot arm 1412 is attached to registration fixture 1410 by, for example,inserting a knob 1416 through an opening 1418 of pivot arm 1412.

Using pivot arm 1412, registration fixture 1410 may be placed over thetargeted anatomical structure and its location may be determined in animage space and navigation space using tracking markers 1420 and/orfiducials 1422 on registration fixture 1410. Registration fixture 1410may contain a collection of markers 1420 that are visible in anavigational space (for example, markers 1420 may be detectable bytracking subsystem 532). Tracking markers 1420 may be optical markersvisible in infrared light as previously described herein. Registrationfixture 1410 may also contain a collection of fiducials 1422, forexample, such as bearing balls, that are visible in an imaging space(for example, a three dimension CT image). As described in greaterdetail with respect to FIG. 11 , using registration fixture 1410, thetargeted anatomical structure may be associated with dynamic referencebase 1404 thereby allowing depictions of objects in the navigationalspace to be overlaid on images of the anatomical structure. Dynamicreference base 1404, located at a position away from the targetedanatomical structure, may become a reference point thereby allowingremoval of registration fixture 1410 and/or pivot arm 1412 from thesurgical area.

FIG. 11 provides an exemplary method 1500 for registration consistentwith the present disclosure. Method 1500 begins at step 1502 wherein agraphical representation (or image(s)) of the targeted anatomicalstructure may be imported into system 100, 300 600, for example computer408. The graphical representation may be three dimensional CT or afluoroscope scan of the targeted anatomical structure of the patient 210which includes registration fixture 1410 and a detectable imagingpattern of fiducials 1420.

At step 1504, an imaging pattern of fiducials 1420 is detected andregistered in the imaging space and stored in computer 408. Optionally,at this time at step 1506, a graphical representation of theregistration fixture 1410 may be overlaid on the images of the targetedanatomical structure.

At step 1508, a navigational pattern of registration fixture 1410 isdetected and registered by recognizing markers 1420. Markers 1420 may beoptical markers that are recognized in the navigation space throughinfrared light by tracking subsystem 532 via position sensor 540. Thus,the location, orientation, and other information of the targetedanatomical structure is registered in the navigation space. Therefore,registration fixture 1410 may be recognized in both the image spacethrough the use of fiducials 1422 and the navigation space through theuse of markers 1420. At step 1510, the registration of registrationfixture 1410 in the image space is transferred to the navigation space.This transferal is done, for example, by using the relative position ofthe imaging pattern of fiducials 1422 compared to the position of thenavigation pattern of markers 1420.

At step 1512, registration of the navigation space of registrationfixture 1410 (having been registered with the image space) is furthertransferred to the navigation space of dynamic registration array 1404attached to patient fixture instrument 1402. Thus, registration fixture1410 may be removed and dynamic reference base 1404 may be used to trackthe targeted anatomical structure in both the navigation and image spacebecause the navigation space is associated with the image space.

At steps 1514 and 1516, the navigation space may be overlaid on theimage space and objects with markers visible in the navigation space(for example, surgical instruments 608 with optical markers 804). Theobjects may be tracked through graphical representations of the surgicalinstrument 608 on the images of the targeted anatomical structure.

FIGS. 12A-12B illustrate imaging devices 1304 that may be used inconjunction with robot systems 100, 300, 600 to acquire pre-operative,intra-operative, post-operative, and/or real-time image data of patient210. Any appropriate subject matter may be imaged for any appropriateprocedure using the imaging system 1304. The imaging system 1304 may beany imaging device such as imaging device 1306 and/or a C-arm 1308device. It may be desirable to take x-rays of patient 210 from a numberof different positions, without the need for frequent manualrepositioning of patient 210 which may be required in an x-ray system.As illustrated in FIG. 12A, the imaging system 1304 may be in the formof a C-arm 1308 that includes an elongated C-shaped member terminatingin opposing distal ends 1312 of the “C” shape. C-shaped member 1130 mayfurther comprise an x-ray source 1314 and an image receptor 1316. Thespace within C-arm 1308 of the arm may provide room for the physician toattend to the patient substantially free of interference from x-raysupport structure 1318. As illustrated in FIG. 12B, the imaging systemmay include imaging device 1306 having a gantry housing 1324 attached toa support structure imaging device support structure 1328, such as awheeled mobile cart 1330 with wheels 1332, which may enclose an imagecapturing portion, not illustrated. The image capturing portion mayinclude an x-ray source and/or emission portion and an x-ray receivingand/or image receiving portion, which may be disposed about one hundredand eighty degrees from each other and mounted on a rotor (notillustrated) relative to a track of the image capturing portion. Theimage capturing portion may be operable to rotate three hundred andsixty degrees during image acquisition. The image capturing portion mayrotate around a central point and/or axis, allowing image data ofpatient 210 to be acquired from multiple directions or in multipleplanes. Although certain imaging systems 1304 are exemplified herein, itwill be appreciated that any suitable imaging system may be selected byone of ordinary skill in the art.

Referring now to FIGS. 13A-15 of the present disclosure, exemplaryembodiments of a surveillance marker consistent with the presentdisclosure are illustrated. FIGS. 13A-13B depicts a system 2000including a surveillance maker 2002, a dynamic reference base (DRB)2004, which may be a tracking array having array markers 2006, a DRBpost 2008, and a surveillance marker post 2010. Also depicted is apatient's bone 2012. In this configuration, surveillance marker 2002 ison surveillance marker post 2010 that is within the hollow center orchannel of the main shaft of the DRB post 2008. Surveillance marker post2010 could consist of hard metal with a sharp, smooth tip for drivinginto bone with a mallet, or an end-threaded tip for drilling into bone.If DRB 2004 is bumped or dislodged, the tracking array with arraymarkers 2006 would shift relative to the position of surveillance marker2002 despite the close proximity of the spikes holding DRB 2004 to bone2012 and the tip of the surveillance post 2010 for the surveillancemarker 2002. Post 2010 to which surveillance marker 2002 is mounted iswithin the hollow main shaft of a spike or clamp to which DRB 2004 ismounted. There may be a loose tolerance between the wall of the hollowmain shaft of DRB post 2008 and surveillance marker post 2010.

In the exemplary embodiment of FIG. 13A, with surveillance marker post2010 encompassed by DRB post 2008, dislodgment and bending movement ofDRB 2004 may cause DRB 2004 to press against surveillance marker post2010 and cause it to move as well. However, since the attachment orentry point to bone 2012 is different for DRB post 2008 and surveillancemarker post 2010, the axis of rotation of surveillance marker post 2010and DRB 2004 may differ, meaning there may be a detectable change inposition of surveillance marker 2002 relative to DRB 2004 even if thetwo structures touch. The amount of relative shift in position ofsurveillance marker 2002 and tracking markers 2006 if DRB 2004 is bumpedmay be greatest if surveillance marker post 2010 does not touch theinside wall of the hollow shaft of DRB post 2008. It may be beneficialto have a loose tolerance between surveillance marker post 2010 andinside wall of the DRB post 2010 for a more easily detectable effect. Itmay also be beneficial to at least begin surveillance with a conditionwhere surveillance marker post 2010 is not touching the hollow wall ofDRB post 2004, even if it will eventually touch during bending. To helpensure that surveillance marker post 2010 is not touching the hollowwall of DRB post 2008 during insertion, it may be beneficial to use atemporary centering guide such as a doughnut-shaped piece, through whichsurveillance marker post 2008 is inserted and which forces thesurveillance marker post to the midline of the hollow shaft. After thepost is inserted, the guide could be removed so that there remains loosetolerance between the hollow wall of the DRB post 2008 and surveillancemarker post 2010. Such a guide could be used at the top of the DRB'stube region, at the bottom of the tube region, or both.

FIG. 13B is another configuration of system 2000 with surveillancemarker 2002 offset from the midline of DRB post 2008. This configurationmay avoid inadvertent rotation of the clamped DRB 2004 about the axis ofthe shaft when bumped. Such rotation may occur if clamp 2014 holding DRB2004 in place is not sufficiently tightened and DRB 2004 is disturbed,even slightly. In the exemplary embodiment of FIG. 13A, if rotation ofDRB 2004 about DRB post 2008 occurred without any travel of DRB 2004longitudinally along DRB post 2008, there may be minimal or undetectablerelative movement of surveillance marker 2002 during rotationaldislodgement since the position of surveillance marker 2002 is on orclose to the axis of rotation of DRB 2004 rotational movement. In thisevent, surveillance marker 2002 may be offset from the midline orlongitudinal axis of DRB post 2008 (for example by 1 cm or more), asshown in FIG. 13B. In this configuration, even a slight rotation of DRB2004 about its mounting shaft would be detectable relative to theunmoved surveillance marker 2002, since surveillance marker 2002 is noton the axis of rotation of DRB 2004. This configuration may also give adistal region on surveillance marker post 2010 that can serve as thehead to be struck with a hammer for driving it into bone, or a region toclamp in the chuck of a drill if it is to be drilled into bone. Ifsurveillance marker 2002 is attached centrally to post 2010, a cap orother feature may be added to allow it to be inserted without damagingthe surface of surveillance marker 2002, which may be coated withreflective paint. Additionally, during insertion, this configuration mayallow surveillance marker 2002 to be manually rotated and positionedpointing toward the tracking cameras for better visibility.

FIGS. 14A-B illustrates an exemplary embodiment of a system 2100 thatincludes some components as previously described. System 2100 alsoincludes a temporary grouping element 2102. In system 2100, surveillancemarker 2002 may be attached through the same incision into a patient,but not physically connected to DRB 2004 or DRB post 2008. One manner todo this may be to use temporary grouping element 2102 to holdsurveillance post 2010 and DRB post 2008 so that these components may beinserted as a unit. These components may then become independent aftertemporary grouping element 2102 is removed as shown in FIG. 14B.

In FIG. 14A, DRB post 2008 and surveillance marker post 2010 may beinserted into bone 2012 simultaneously while being held together at adesired spacing with temporary grouping element 2102. After DRB post2008 and surveillance marker post 2010 have been inserted, temporarygrouping element 2102 may be removed, and DRB 2004 and surveillancemarker 2002 may be attached, which may be anchored in independent piecesof bone. Temporary grouping element 2102 may also be an impaction cap tobe struck by a hammer during insertion.

FIG. 15 illustrates an exemplary embodiment 2200. In this configurationit may be possible to attach surveillance marker 2002 through the sameincision of the patient but not physically connected to DRB 2004. InFIG. 15 , different insertion angles may be used, with trajectories ofthe surveillance marker post 2010 and DRB post 2008 within the sameincision (not shown).

The attachment of surveillance marker 2002 as described with regard toFIGS. 13-15 may allow application of a surveillance marker, which hasdemonstrated benefits, through a single incision instead of requiringmultiple incisions which may result in less time in surgery and lessdiscomfort for the patient.

Now turning to FIGS. 16A and 16B, there is shown a surveillance marker2020 that is used to detect any change of position of the dynamicreference base (DRB) 2024, which is critical for navigational accuracy.In some situations, the surveillance marker 2020 may not be able todetect a position change correctly if a DRB rotates along an axis 2026,and the surveillance marker 2020 is close to or on the axis of rotation2026. The change of position appears as a rotation of the surveillancemarker 2020, which does not register as a position change, since thesurveillance marker 2020 is a configured as a sphere.

The surveillance marker 2020 as illustrated in FIGS. 16A and 16B, uses asingle optical marker 2028, typically a sphere, ‘registered’ to the DRB2024. Both surveillance marker and DRB are securely attached to bonyanatomy with a separate post or spike. The position of the surveillancemarker is tracked with respect to the DRB 2024 coordinate system, sothat any shift or rotation of the DRB 2024 (or any shift of thesurveillance marker) can be detected, even if the camera is moved. Thisscheme works well in any situation involving a purely translationalshift.

FIGS. 16A and 16B show how a single surveillance marker fails to detectthe rotation of an array on a DRB if the DRB mounts to the patient witha hinge mechanism and the hinge's axis of rotation intersects thesurveillance marker. However, if more than one surveillance marker isused, the system can successfully detect a rotation, if the axis ofrotation of the DRB does not pass through all the surveillance markers.In one exemplary embodiment, this mechanism would utilize two opticalmarkers on the surveillance instrument, which could attach to the samepost as shown in FIGS. 17A and 17B to minimize surgical incisions ormounted to different posts. In this embodiment, a surveillance marker2030 is provided with at least two optical markers 2032, 2034. Thesystem could use the relative distance between each of optical markers2032, 2034 and the DRB, or between the line formed by the two markers2032, 2034 and the DRB markers, to calculate the amount of shift.Surveillance markers mounted to a post vertically or mostly verticallyas shown in FIG. 17 will most likely not both be collinear with a hingethat is oriented horizontally. In other embodiments, three or moremarkers may be used to create accuracy through redundancy.

Now turning to FIG. 18 , in a preferred embodiment, the system through asoftware element may alert the user that a single surveillance marker2040 is in close proximity to the axis of rotation of the DRB 2042 ifthe location of the DRB's hinge 2044 is known relative to the trackedmarkers of the DRB 2042 and hinge location is extrapolated and comparedto the surveillance marker position 2040. If the surveillance marker2040 is close to the hinge, for example in one embodiment less than 25mm from the hinge, the system can alert the user to move thesurveillance marker or use a secondary method such as landmark check totest whether there is any rotational movement. Similarly, the system canalert the user if dual surveillance markers form a line that is close tobeing collinear with the hinge of the DRB.

In another embodiment, the system provides a method of ensuring that theDRB hinge does not intersect the surveillance marker by restrictingwhere the user can mount the surveillance marker to force thesurveillance marker to be located away from the DRB's hinge. In oneparticular embodiment, a collar clamp on the DRB shaft with a small postpresent for the attachment of a single surveillance marker is used (FIG.3 ). There are markings provided on the DRB shaft and physical stopsalong the shaft or collar, or in another embodiment a wide collar clampdesign ensure that the surveillance marker is never able to be mountedfar enough up the shaft that it would approach the location of thehinge.

In another embodiment, there is a provided a method of preventing thesurveillance marker from approaching the hinge. A temporary guide tubeis utilized wherein the temporary guide tube has a minimum allowableradius to the hinge during setup, blocking the user from placing thesurveillance marker within that radius of the hinge.

In yet another embodiment, a chain or other tether to the base of theDRB with the surveillance marker attached to the other end could be usedthat will not allow the surveillance marker to approach the hingelocation.

When the DRB is displaced either accidentally or by need, the presentsystem provides a method of monitoring skin movement. In one embodiment,the skin may be marked with ink 2040 or any other bio-compatiblematerial or a second surveillance marker may be attached to the skin(FIG. 3 ). If a first surveillance marker is already near the skin, likein the previous, embodiment, the mark on the skin can be placed verynear the post-mounted marker. The system would be able to use the firstsurveillance marker mounted to the DRB post to track DRB shift androtation, while the surgeon would visually monitor the patient's skinmark to track shift (tugging) of the skin immediately surrounding theDRB. The close proximity of the skin mark or the second surveillancemarket to the first surveillance marker makes it is easier to visualizefor the surgeon to discern a shift. If the surgeon suspected that theink mark or the second surveillance marker has shifted, the surgeon oruser can point to the skin mark or the second surveillance marker with atracked probe to determine how much it had moved relative to thelocation of the probe at the beginning of the case. If a tracked markeron the skin is used, this marker can continuously monitor therelationship between the DRB post and the skin to assess whether thereis offset. The above embodiments provide the advantage of tracking theshift in the surveillance marker relative to the DRB even in the caseswhere the shift is in the surveillance marker. In addition, multiplesurveillance markers provide redundancy to the system when line of sightis compromised.

Now turning to another embodiment in which the system provides methodfor recovery of registration from DRBs and single optical markers. Asdiscussed earlier, when navigating using a surgical robotic system,continuous tracking of a DRB array that is attached to the patient isrequired to determine the position of any navigated instrument or toolrelative to the patient's anatomy. Under certain conditions, the DRB maysometimes be partially obscured thereby making the DRB untrackable. Inother situations, the DRB may be dislodged from its mounting point onthe bone, also making it untrackable. When the DRB is partiallyobstructed, tracking or navigating must be paused and the camera systemmodified to restore line of sight to the markers on the DRB. When theDRB is dislodged, a new imaging scan is required and registration of thepatient to the camera coordinate system is done. The present systemprovides a method to recover the registration or enables the continualtracking of optical makers of the surgical robot and the one or moremarkers mounted elsewhere on the patient.

Registration is synchronization of two coordinate systems, typically thetracking coordinate system, such as the coordinate space tracked by anoptical system such as the Polaris Spectra (Northern Digital, Inc.), andthe image coordinate system such as the coordinate system of a computedtomography (CT) scan. Registration is accomplished when the rigid bodytransformation to get from one coordinate system to the other is known.To achieve 3D registration, at least 3 reference points on a rigid bodythat is observed simultaneously in each coordinate system are found andthe transformation of coordinates necessary to move the 3 referencepoints from one coordinate system to their corresponding coordinates inthe other coordinate system is calculated. For example, if a trackingfixture has optical tracking markers that are in a known location (knownfrom engineering design or located by any experimental means) in thefixture's local coordinate system and these tracking markers' xyzlocations are tracked by the cameras, the transformation from cameracoordinate system to fixture coordinate system can be calculated. In thefield of 3D rigid body mechanics, transformations between coordinatesystems are applied by multiplying each point to be transformed by a 4×4transformation matrix. In such matrices, the first three columnsdescribe the orientation of the rigid body and the 4th column describesthe translational offset. The transformation matrix from the cameracoordinate system to the fixture coordinate system may be representedas:T _(Camera-Fixture)

And to transform a point P from the camera coordinate system to thefixture coordinate system is represented as:P _(Fixture) =T _(Camera-Fixture) ×P _(camera)

There are provided several different methods for determining the 4×4transformation matrix from sets of the same points in two coordinatesystems. For example, the Kabsch algorithm is a method for calculatingthe optimal transformation matrix that minimizes the RMSD (root meansquared deviation) between two paired sets of points. Transformationmatrices may be easily combined to achieve new useful transformationmatrices. In one embodiment, the fixture described above may containfiducials for detection within a CT volume. If the locations of thesefiducials are known in the local coordinate system of the fixture, thetransformation of coordinates from fixture to CT image coordinate systemcan be found asT _(Fixture-Image)

-   -   using the Kabsch or similar algorithm. As a result, the        transformation results from the camera coordinate system to the        coordinate system of the medical image can be determined by        combining two transformations:        T _(Camera-Image) =T _(Camera-Fixture) ×T _(Fixture-Image)

If the DRB is dislodged, the relationship between fiducials and the CTare no longer the same as at the time the CT scan was taken, as a resultthe T_(Fixture-Image) is incorrect and T_(Camera-Image) is not valid.

In a preferred embodiment, a tracking array positioned on an endeffector provides the location of the end effector in the coordinatesystem of the cameras. The robot system is equipped with encoders oneach axis that precisely monitor the positions of each linkage of therobot arm. As the robot arm is moved, the position of the end effectoris detected from tracking markers, but the positional change may also becalculated from kinematics by considering the geometry of each joint ofthe robotic arm and the amount of movement on each joint as monitored bythe rotational or linear encoders. This ability to reference points inthe tracking coordinate system from kinematic information provides anadditional transformation calculation that can be utilized: thetransformation from current tracked coordinates of the robot's endeffector to a fixed reference in the camera coordinate system. That is,a frame of tracking data provides a snapshot of the tracked position ofthe robot end effector, but through a transformation derived from theaxis encoder readings that account for the change in position due tomovement of the joints, this moving frame of data can be transformedinto the fixed reference frame of the robot despite any movement of thepatient or camera that may occur. This transformation allows the movingarray on the end effector to function the same as if another array werephysically mounted to the base of the robot to track its position.T _(Camera-RobotBase) =T _(Camera-EndEffector) ×T_(EndEffector-RobotBase)

As described in a previous embodiment a surveillance marker is used tocontinuously monitor the integrity of the DRB's attachment to bone. Ifthe patient moves, both the DRB and the surveillance marker would movetogether without changing their relative position, but if the DRB orsurveillance marker is dislodged, the relative position would change.

In another embodiment, a method for recovering the registration that isbased on the last known position of the DRB relative to the robot isprovided. The system continuously updates the last valid location of theDRB relative to the robot base and stores this location in system memoryfor later usage if necessary.

If the DRB becomes dislodged by inadvertent contact with medicalpersonnel or equipment, the surveillance marker would show a change inoffset of the DRB markers and would positively indicate that movementhad occurred. If tracking data also shows that the distance between therobot's fixed reference frame and the surveillance marker on the patienthave not moved, it can be safely assumed that the patient has not movedrelative to the robot. As a result, the DRB may be reattached and a newregistration established based on the tracked position of the robot. Toestablish a new registration, the new position of the DRB and robot'sarray would be tracked simultaneously, giving the transformationcalculation from the end effector to the new DRB position. Additionally,the last known DRB location in the coordinate system of the robot wouldbe recalled from the memory storage device. The new registration cantherefore be established as:T _(Camera-Image) =T _(Camera-RobotEE) ×T _(RobotEE-RobotBase) ×T_(RobotBase-LastKnownDRB) ×T _(LastKnownDRB-Image)

With the new DRB attachment, the following is also true:T _(Camera-Image) =T _(Camera-DRB) ×T _(DRB-Image)

Setting the two equations equal to each other, the transformation fromnew location of the DRB to the image can be determined asT _(DRB-Image) =T _(DRB-Camera) ×T _(Camera-RobotEE) ×T_(RobotEE-RobotBase) ×T _(RobotBase-LastKnownDRB) ×T_(LastKnownDRB)−Image

During collection of the new location of the DRB in the cameracoordinate system, the location of the surveillance marker relative tothe robot base would be continuously measured to ensure that thesurveillance marker has not moved since before the DRB was dislodged. Inanother embodiment, if there is movement of the surveillance marker ormovement of both the surveillance marker and the DRB at the time ofdislodgment, a new scan and registration would be required.

In another embodiment, the system provides a method for re-registeringthe patient when there is a partial obstruction of the DRB to where only2 of the 4 optical markers on the DRB remain visible while 2 opticalmarkers are blocked. If the robot is movement when there is a partialobstruction, the motion of the robot arm is stopped until the DRBbecomes fully visualized by the camera system, or if a tool orinstrument is being tracked, the tool or instrument would freeze in itsdisplay on the screen. However, the system will track the DRB, if thesurveillance marker remains visible. The two visible optical markers ofthe DRB and the surveillance marker comprise 3 points, which is theminimum points to define a rigid body. If the distances of thesurveillance marker relative to the two visible points have not changed,the DRB has not moved in bone. From any previous frame of data where allmarkers on the DRB were visible, the transformation of the surveillancemarker into the DRB coordinate system could have been determined byapplying the transformation from camera to DRB to the tracked positionof the surveillance marker. This value is stored to the system memory.After the optical markers on the DRB are blocked, the 2 blocked opticalmarkers can be “reconstructed” by applying a point matching algorithmwhere one point set is the tracked xyz coordinates of the two DRBoptical markers plus the surveillance marker and the corresponding pointset to be matched is the same two DRB markers and the surveillancemarker in the coordinate system of the DRB. For example,Point set 1={Visible DRB marker 1,Visible DRB marker 2,Surveillancemarker}_(DRB)Point set 2={Visible DRB marker 1,Visible DRB marker 2,Surveillancemarker}_(Camera) T _(DRB-Camera)

The reconstructed DRB markers are determined as this transformationapplied to the known locations of the missing DRB markers in the DRBcoordinate system:P _(BlockedDRBmarker1,Camera) =T _(DRB-Camera) ×P_(BlockedDRBmarker1,DRB)P _(BlockedDRBmarker2,Camera) =T _(DRB-Camera) ×P_(BlockedDRBmarker2,DRB)

Using a full set of the two previously visible DRB optical markers plusthe two reconstructed markers, the normal sequence of transformationscan be applied and standard tracking methods followed.

While the invention has been disclosed in connection with the preferredembodiments shown and described in detail, various modifications andimprovements thereon will become readily apparent to those skilled inthe art. Accordingly, the spirit and scope of the present invention isnot to be limited by the foregoing examples, but is to be understood inthe broadest sense allowable by law.

What is claimed is:
 1. A system for monitoring registration of a patientto a surgical robot, said system comprising: a tracking camera system; asurgical robot having a base, arm attached to the base and an endeffector attached to the arm; robot tracking markers disposed on thesurgical robot for tracking movement of the surgical robot by thetracking camera system; a dynamic reference base (DRB) including amarker array trackable by the tracking camera system, the marker arraybeing an optical marker array; a dynamic reference base post connectedto the DRB; and a surveillance marker adapted to be disposed at apredetermined distance from the DRB and trackable by the tracking camerasystem, wherein the surveillance marker is configured to be secured tothe patient independently from the dynamic reference base and is anoptical marker, wherein the surveillance marker is mechanically notconnected to the dynamic reference base, a processor configured tocontinuously monitor the locations of the surveillance marker, the DRBmarker array and the robot tracking markers through the tracking camerasystem, and to detect whether registration is lost from movement of theDRB relative to the surveillance marker and if so, automaticallyestablish a new registration based on the tracked locations of thesurveillance marker and the robot tracking markers without re-scanningwith an imaging device.
 2. The system of claim 1, wherein thesurveillance marker is off-set from a longitudinal axis of the dynamicreference base post.
 3. The system of claim 1, wherein the surveillancemarker is disposed on a surveillance marker post, wherein thesurveillance marker post is disposed in a hollow channel of the dynamicreference base post.
 4. The system of claim 1, further comprising asurveillance marker post associated with the surveillance marker,wherein the surveillance marker post is metal and contains a sharp tipconfigured to drive into the bony structure.
 5. The system of claim 1,wherein the DRB includes at least three DRB markers and the processor isconfigured to detect a loss of tracking at least one of the DRB markerswhile maintaining tracking of at least two of the DRB markers and if so,maintain registration based on the tracking of the surveillance markerand the at least two of the DRB markers without re-registration.
 6. Thesystem of claim 5, wherein the processor determines that the dynamicreference base has moved based on a change in the predetermineddistance.
 7. The system of claim 1, wherein the robot tracking markersare disposed on the end effector.
 8. The system of claim 7, wherein theprocessor is configured to automatically establish the new registrationbased on the tracked locations of the robot tracking markers on the endeffector and an encoder position in the surgical robot arm.
 9. Thesystem of claim 1, further comprising a surveillance marker postassociated with the surveillance marker, wherein the surveillance markerpost is adapted to be disposed in the bony structure at an anglerelative to dynamic reference base post.
 10. The system of claim 9,wherein the surveillance marker post and the dynamic reference post areconfigured to be inserted into a single incision.
 11. A system formonitoring registration of a patient to a surgical robot, said systemcomprising: a tracking camera system; a surgical robot having a base,arm attached to the base and an end effector attached to the arm; robottracking markers disposed on the surgical robot for tracking movement ofthe surgical robot by the tracking camera system; a dynamic referencebase (DRB) including a marker array trackable by the tracking camerasystem, the marker array being an optical marker array; a dynamicreference base post associated with the DRB; a surveillance markerdisposed at a predetermined distance from the dynamic reference base andbeing a single optical marker, wherein the surveillance marker ismechanically not connected to the dynamic reference base; a surveillancemarker post on which the surveillance marker is disposed; wherein thesurveillance marker post and the dynamic reference base are adapted tobe attached to a bony structure at different entry points, a processorconfigured to continuously monitor the locations of the surveillancemarker, the DRB marker array and the robot tracking markers through thetracking camera system, and to detect whether registration is lost frommovement of the DRB relative to the surveillance marker and if so,automatically establish a new registration based on the tracked locationof the surveillance marker and the last known tracked location of therobot tracking markers without re-scanning with an imaging device. 12.The system of claim 11, wherein the surveillance marker is off-set froma longitudinal axis of the surveillance marker post.
 13. The system ofclaim 11, wherein the surveillance marker post and the dynamic referencebase post are adapted to be inserted into a single incision.
 14. Thesystem of claim 11, wherein the surveillance marker post is metal andcontains a sharp tip configured to drive into the bony structure. 15.The system of claim 11, wherein the dynamic reference base post includesone or more spikes to attach to the bony structure.
 16. The system ofclaim 11, wherein the DRB includes at least three DRB markers and theprocessor is configured to detect a loss of tracking at least one of theDRB markers while maintaining tracking of at least two of the DRBmarkers and if so, maintain registration based on the tracking of thesurveillance marker and the at least two of the DRB markers withoutre-registration.
 17. The system of claim 16, wherein the processordetermines that the dynamic reference base has moved based on a changein the predetermined distance.
 18. The system of claim 16, wherein thesurveillance marker and the at least three DRB markers are each anoptical marker configured to be recognized by the tracking camerasystem.
 19. The system of claim 11, wherein the robot tracking markersare disposed on the end effector.
 20. The system of claim 19, whereinthe processor is configured to automatically establish the newregistration based on the tracked locations of the robot trackingmarkers on the end effector and an encoder position in the surgicalrobot arm.